Histology of the Upper Respiratory Tract Nasal cavity

Histology of the Upper Respiratory Tract (Nasal cavity, Paranasal sinuses and Larynx) Color index: Slides. . Important. . Notes. . Extra. .

Objectives : By the end of this lecture the student should be able to describe the microscopic structures of: üVestibule of the nasal cavity. üRespiratory mucosa of the nasal cavity. üNasal septum. üOlfactory mucosa of the nasal cavity. üMucosa of the paranasal sinuses. üLarynx.

RESPIRATORY SYSTEM A- Conducting portion : o o o o Nasal cavity. Nasopharynx. Larynx. Trachea. Primary bronchi (extrapulmonary bronchi). Intrapulmonary bronchi: o - 2 ry bronchi (lobar bronchi). o - 3 ry bronchi (segmental bronchi). Primary bronchioles (preterminal bronchioles). Terminal bronchioles. B- Respiratory portion: o o Respiratory bronchioles. Alveolar ducts are tiny ducts Alveolar sacs. that connect the respiratory Pulmonary alveoli bronchioles to alveolar sacs

NASAL CAVITY Anterior portion of N. C Posterior portion of N. C Vestibule Respiratory region Olfactory region VESTIBULE OF N. C Lining is lined with thin skin. 1 - Epidermis: (Keratinized stratified epithelium). Squamous 2 - Dermis. Contents 1 - Vibrissae: stiff hairs. 2 - Sebaceous glands. ﻏﺪﺩ ﺩﻫﻨﻴﺔ 3 - Sweat glands. N. B. The nasal septum (made from cartilage + spongey bone) divides the nasal cavity into two halves (right and left). Wall Olfactory region is found in the roof of the nasal cavity and the upper part of nasal septum and it is abundant in water secretory vesicles in order to dissolve the odor producing chemicals 1 - Hyaline cartilage. 2 - Cancellous (spongy) bone. .

RESPIRATORY REGION (Area) OF NASAL CAVITY MUCOSA (mucous membrane) The respiratory area of the nasal cavity is made up of two components: A) Epithelium: Pseudo-stratified ciliated columnar epithelium with goblet cells (Respiratory epithelium). begins in the posterior nasal cavity B) Lamina propria ( Sub-epithelial C. T. ): contains: 1 - Large arterial plexuses & venous sinuses (Highly vascularized C. T. ) 3 - Many seromucous glands (acini). Watery secretions 4 - Abundant lymphoid elements: Including occasional lymphoid nodules , plasma cells & mast cells. Mucous membrane = epithelium + lamina propria (vascularized connective tissue layer) Respiratory Epithelium Is made of pseudo-stratified ciliated columnar epithelium with goblet cells. This epithelium consists of multiple types of cells mainly : (all touch basement membrane) o Ciliated columnar cells. Short and tall but only the ones that reach surface are ciliated o Goblet cells. o Basal cells (stem cells). o DNES cells e. g. Serotonin Functions : it serves to moisten and protect the airways. It also functions as a barrier to potential pathogens and foreign particles, preventing infection and tissue injury by the action of mucociliary clearance.

PARANASAL SINUSES Lining: 1 - Respiratory epithelium. (Pseudo-stratified ciliated columnar epithelium with goblet cells ) 2 - Lamina propria. CLINICAL APPLICATION: Sinusitis is characterized by inflammation of the lining of the paranasal sinuses. Because the nasal mucosa is simultaneously involved and because sinusitis rarely occurs without concurrent rhinitis, rhinosinusitis is now the preferred term for this condition.

OLFACTORY region of nasal cavity Olfactory Mucosa is made up of two components : 1)OLFACTORY EPITHELIUM: o Pseudo-stratified columnar epithelium. (no goblet cells!) o Olfactory cells (olfactory nerve cells) o Sustentacular (supporting) cells. o Basal cells: Pyramidal in shape, basal in position and act as stem cells. (neurons cannot divide due to lack of centrioles thus it needs stem cells for annual renewal) OLFACTORY CELLS o Are bipolar neurons o Dendrite has olfactory vesicle that has nonmotile cilia. Sterocilia o Axons are unmyelinated with Schwann-like cells. o Axons will collect in the lamina propria to form bundles of nerve fibers. Bundles will collect to form the olfactory nerve SUSTENTACULAR (SUPPORTING) CELLS are columnar cells. Function: Physical support and nourishment (metabolic) for olfactory cells. Site of olfactory region: 1)Roof of nasal cavity. 2)Upper part of nasal septum. 3)over superior concha. 2)LAMINA PROPRIA: Highly vascular loose to dense C. T. Contains: o Bowman’s glands (olfactory glands): serous acini. o Bundles of unmyelinated nerve fibers. o axons of olfactory nerve cells + Schwann-like cells (glial cells). pure serous , no mucus secretion o Rich vascular plexus. o Numerous lymphoid elements

Larynx Epithelium (2 types): -Mucosa (Mucous membrane) 1. Respiratory Epithelium (Pseudostratified Ciliated Columnar Epithelium With Goblet Cells). Lamina Propria 2. Non Keratinized Stratified Squamous Epithelium Found In: Vocal Folds (Cords) And Superior Surface Of epiglottis. -Cartilages Elastic cartilages e. g. Epiglottis -Extrinsic and intrinsic muscles All Are Skeletal Hyaline cartilages e. g. Thyroid cartilage -Ligaments Vestibular Folds "Are Immovable" There are 2 pairs of Shelf-like Mucosal Folds in larynx. Vocal Folds (Cords) Epithelium: Respiratory epithelium Epithelium : Non keratinized stratified squamous epithelium Lamina propria: Loose C. T. With seromucous glands Lymphoid elements Adipose cells Lamina propria : C. T. containing bundles of elastic fibers and skeletal muscle. NO Lymphoid nodules - NO Seromucous glands

Pictures for further understanding

Still confused ? Please read this. Ok so as you all should know by now the respiratory system is divided into 2 zones 1)Conducting 2) respiratory , each of them are composed of several organ or parts that serve their function. In this lecture we talked about the nasal cavity and larynx which are both part of the conducting zone , meaning that their function is to pass or transport air to the lungs acting as passages. The nasal cavity the nasal cavity has 2 main functions smelling (olfactory) and as passage ways for cleaning and humidifying air (respiratory)so it is further divided to 2 regions 1) olfactory region 2) respiratory region. Both these are composed of different mucosa to serve their function , put in mind that all mucosa consists of two parts (epithelium + lamina propria). Both these regions exist in the posterior portion on nasal cavity (remember nasal cavity is primarily divided to anterior and posterior portions ). Olfactory region is present in the upper part of posterior portion of the nasal cavity , while respiratory region is present in the back of this portion. Olfactory region Epithelium : 4 types of cells ( no cilia but is has cilia like dendrites from olfactory cells). No goblet cells. Lamina propria : doesn't have any mucus glands but it has bowman’s gland that secrete water like fluids. Respiratory region Epithelium : multiple types of cells. Goblet cells are present. Special cells : DNES are present. Lamina propria : seromucous glands the secrete watery mucous. What are the difference between bowman’s gland seromucous glands ? Bowman gland has water (serum) like secretion. Seromucos gland’s secretion is between water and mucous consistency ( thicker than bowman’s ) (not completely mucus nor completely watery ) Larynx Why does the superior part of epiglottis (in contact with esophagus)have stratified epithelium and not pesudostratified ? Imagine eating something hot and you accidently burn the first layer of epithelium ? If it were to be pseudostartifed (one layer ) than food will directly contact the vascular tissue beneath the epithelium causing you to bleed in seconds. That is why its is composed of stratified epithelium (multiple layers) so it can protect the vascular layer beneath Same goes for the vocal cords incase of edema or swelling the vocal cords may contact the false cords causing friction which will damage the epithelium causing the person to bleed. That is why it is covered with stratified epithelium

Mind Map Special thanks to Norah Al. Shabib

Links to help you ! Videos : Nasal cavity and larynx : https: //www. youtube. com/watch? v=bk. SZUHs. G 1 No&t=57 s Full playlist for respiratory system : https: //www. youtube. com/watch? v=23_a. Ho 4 X 2 Vs&list=PLEf 8 wm. Jp. S_1 Hmyw. DPF 1 Ve 0 z. Rh. Wf. HCH COy FULL MIND MAP

MCQ : 1 - Respiratory bronchioles are part of both respiratory and 6 - The olfactory epithelium contain all of conducting portion these except A- T B- F 2 - The epithelium of the vocal cord is A- Pseudo-stratified ciliated columnar epithelium with goblet cells B- Pseudo-stratified non-ciliated columnar epithelium without goblet cells C- Keratinized stratified Squamous epithelium D- non- Keratinized stratified Squamous epithelium 3 - Epiglottis made of A- hyaline cartilage B- elastic cartilage C- fibrocartilage 4 - Vestibule lined by respiratory epithelium A- T B- F 5 - The lining of paranasal sinuses is A- respiratory epithelium B- both Pseudo-stratified ciliated columnar epithelium with goblet cells & skin C- endothelium same as vessels A- sustentacular cell B- basal cell C- bowman’s gland D- olfactory cell 7 - Pyramidal in shape and act as stem cell A- sustentacular cell B- basal cell C- goblet cell D- olfactory cell 8 - axons of olfactory nerve cells are unmyelinated A- T B- F 9 - vocal folds contain all of these except A- elastic fibers B- skeletal muscles C- lymphoid nodules D- lamina propria 1 - B 2 - D 3 - B 4 - B 5 - A 6 - C 7 - B 8 - A 9 - C

Thank you & good luck - Histology team Done by : We’am Babaier Rema Albarrak Amal Al Qarni Shahad Alanzan Team leaders: Reema Alotaibi Faisal Alrabaii Please if you need anything or even further explanation contact us on : Histology. Team 436@gmail. com @histology 436